The present invention relates to a process for converting benzene or derivatives thereof to phenol or related compounds, and also relates to improved catalysts for use in that process.
Phenol or a derivative thereof can be produced by a single-step oxidative hydroxylation of benzene or a derivative thereof, using nitrous oxide over a catalyst. For example, PCT publication WO 9527560 describes such a process that employs a zeolite catalyst whose performance is enhanced by hydrothermal treatment.
The catalyst that is used in such a process has to be regenerated periodically. One problem with the regeneration step is that it generates carbon monoxide. Because emissions of carbon monoxide into the atmosphere are limited by environmental regulations in the United States and other countries, when this compound is produced during catalyst regeneration it must be recovered and/or converted to another compound. These additional steps make the overall process more expensive.
A need exists for improved catalysts for conversion of an aromatic hydrocarbon such as benzene to phenol or another desired product. In particular, a need exists for catalysts that can be used in such processes with good activity, stability, and selectivity, and that would also reduce the amount of carbon monoxide created during catalyst regeneration.